Saw sharpening device

ABSTRACT

A device for sharpening a circular knife or saw which provides a support for the knife and is tiltable to bring the knife into and out of contact with a grinding wheel. The invention includes mechanism for turning the knife to present the next tooth or section of the knife for grinding and which includes means for counting the sections as they are sharpened and turns the device off when all sections have been sharpened. Automatic driving means are included which produce these functions in proper sequence. Included also are permanent magnets for holding the knife against vibration while still permitting turning, and a special carriage for the rod in the knife turning mechanism to keep the rod in its intended longitudinal movement.

3,766,806 1 Oct. 23, 1973 SAW SHARPENING DEVICE Inventor: Lloyd Robert Benner, Nampa, Idaho Armour and Company,

Chicago, Primary Examiner-Andrew R. .luhasz [73] Assignee:

[22] Filed; No 8, 1971 Assistant Examiner-James F. Coan [21] AttorneyFrank T. Barber et al.

Appl. No.: 196,462

ABSTRACT 76/43 51 Int.

A device for sharpening a circular knife or saw which provides a support for the knife and is tiltable to brin the knife into and out of contact with .a

269/8, 279/1 'M B23d 63/14 76/42, 45, 37, 47,

E grinding r turning [58] Field of Search 76/48, 43; 279/1 M; 269/8; 51/225 wheel. The invention includes mechanism fo the knife to present the next tooth or section of the knife for grinding and which includes means for counting the sections as the the device off when all sec [56] References Cited UNITED STATES PATENTS y are sharpened and turns tions have been shar pened.

.l w wm wm mi mw P m m a C 6M nam n k w e.m m m Automatic driving means are included which these functions in proper sequence. lnclucled permanent magnets for holdin bration while still permitting carriage for the rod in the knife turnin keep the rod in its intended longitudinal movement.

10 Claims, 5 Drawing Figures 220333332X 44 444444 ////////8 66666666] 77777777 mu mm mm2 FIGJ SHEET 2 OF 2 PATENTEB [1m 2 3 197a FIG.3

SAW SHARPENING DEVICE SUMMARY This invention relates to a device for sharpening circular disc cutters or saws, and more particularly the circular skinning knives which have come into extensive use in the meat packing industry. ln this disclosure the term knife is used to include the circular disc type cutting elements, whether the teeth be formed specifically for cutting, tearing or shearing. The circular disclike cutters having teeth about their cylindrical edges are commonly placed face to face and rotated in oppo site directions to provide a shearing cutting action.

BACKGROUND Circular knives have found wide application in the packing industry for skinning hides from carcasses of animals. These are disc-like in form, have a central aperture and have teeth or serations about their outer circular edges. It is imperative that these knives be kept sharp and frequent sharpening is necessary.

Traditionally, the sharpening of such knives has been done by hand, and is work which can be done properly only by a person highly skilled. The equipment available has included a table carried by a tiltable arm. To use this equipment the operator would place the knife to be sharpened on the table and then with his fingers press the table about its pivot to press the blade against the rotating grinding wheel. When one notch on the knife has been sharpened the operator then would turn the disc by hand so that the next adjacent notch in the knife would be turned on grinding position. The bite of the grinding wheel against the knife being sharpened is, in such operation, governed largely by the amount of pressure applied by the hands of the operator. This operation has left much to be desired because both the placing and the depth of the cut was dependent on the skill of the operator and the sensitivity of human hands to slight differences in pressure. Furthermore, the sharpening of knives in the traditional way was a tedious, time consuming task, and few persons develop the skill and have the patience to do a good job.

Accordingly, itisan object of this invention to provide a sharpening device which will automatically sharpen knives of the circular disc type so as to eliminate the variations in result which accompany hand sharpening, and to eliminate the time consuming and tedious task of hand sharpening.

A further object of the invention is to provide a device which will hold a circular type cutting knife with sufficient firmness to keep it in position while one tooth or section of the knife is being ground, but which will allow it to be turned precisely to present the next tooth at the proper position for grinding.

Yet another object is to provide a sharpening device for circular knives which includes mechanism for turning the knives precisely and without variation to a position in which, following the grinding of one tooth, the next tooth is presented accurately for sharpening.

Additional objects and advantages of the invention will become apparent as this specification proceeds.

DETAILED DESCRIPTION One embodiment of this invention is illustrated by the accompanying drawings, in which FIG. 1 is a perspective view of the device taken from the top side;

FIG. 2 is another perspective view showing particularly the tiltable support for the table which holds the knives as they are sharpened;

FIG. 3 is a detail perspective view showing the cam mechanism fordriving various automatic functions of the device;

FIG. 4 is a perspective view of the counting mechanism on the back side of the device; and

FIG. 5 is a detail view in side elevation showing a part of the mechanism for turning the knife blades, and showing particularly the mounting of the rod in the frame.

The device, as illustrated, includes a frame including a base plate 11 on which the motor 12 is mounted. The motor 12 drives the grinding wheel 13 through shaft 14. The motor 15 operates through gears 16 and shafts 17 and 18 to drive the shaping wheel 19. Wheel 19 has a center ridge 19a on its edge which corresponds to the channeled edge 20 of grinding wheel 13, and adjusting apparatus 21 is provided for moving the edge of the shaping wheel 19 against the edge of grinding wheel 13 with sufficient pressure that when these wheels are turned with respect to each other, preferably in opposite angular directions, the shaping wheel forms the edge of the grinding wheel in a proper shape for grinding one tooth of a knife to be sharpened.

The motor 15 and shaping wheel 19 are operated only on occasion to keep the grinding wheel in proper shape for its function of grinding individual teeth in the knives to be sharpened.

The table along with its tiltable support, is more clearly shown in FIG. 2. As shown, table 30 is carried on the forward portion of arm 31 which is slideably secured on the arm piece 32 which is tiltably carried on pin 33 between bearings 34. The bearings are secured through block 35 to base 11. Adjusting apparatus 36 is provided for moving arm 31 forwardly or rearwardly as needed for positioning table 30.

Cam 37, under arm 31, provides a lower stop for the arm, and the adjusting apparatus 38 operates to turn cam 37 thus to adjust the extent to which arm 31 can move forwardly about its pivot. This adjustment is provided so that the knife being sharpened will be moved into just the right position to be ground by wheel l3 when the arm has reached the limit of its forwarding tilting movement.

The table 30, which is carried by the forward end of arm 31, has a central hub 39 which :is of a size to fit the central aperture in the knife to be sharpened, and this hub extends through the knife aperture and serves to guide theknife when it is turned angularly to present different sections of the knife for sharpening. The fore part of the table is cut away at 40 so that the edge of the knife to be sharpened will be free and contact will be made with the grinding wheel.

Near the side edges of table 30 are the permanent magnets 41 and 42 which are secured within openings in the table 30. It is an important feature of this invention that these magnets are provided to draw the surface of the knife to be sharpened against the surface of the table so as to provide a frictional engagement be tween the knife and the table. It is further desirable that the magnets be spaced as shown in the drawing with each magnet near the edge portion of the knife.

The mechanism for driving the device in its various functions is shown more clearly in FIGS. 1 and 3. An electric motor 45 is carried by frame plate 11. The

switch box 46, also carried in the frame, contains the electrical connections for starting and stopping motor 45. Motor 45, through gearing 47, drives the transverse shaft 48, on which are carried the cams 49, 50 and 51.

Pressing against cam 49 is the strap 60 (see FIGS. 3 and A spring 61 pulls this strap rearwardly against cam 49 but allows the strap to move forwardly when pressed by the cam. Strap 60 is connected to the forwardly extending rod 62. Rod 62 is square in cross section and moves forward and back within the channels of rollers 63. Rollers 63 are rotatably mounted on frame member 64 carried by base plate 11. Three of rollers 63 are provided, two below and one above the rod 62, so as to hold the rod in alignment while permitting it to move freely in a longitudinal direction.

At its forward end rod 62 has a detent 65, and when this rod moves forwardly the pointed slanted portion of the detent catches a tooth of the knife to be sharpened and thus turns the knife angularly about hub 39 until the next tooth of the knife is in position for grinding. When the cam 49 has moved to present its low side 49a to the strap, the rod 31 will move back urged by spring 61 with the point of detent 65 moving back along the slanted edge of the knife tooth.

Cam 50 bears against lever 70 which is pivotally mounted on base 11 by means of the pin 71 and brackets 72. The forward end of this lever extends to a position under arm 31 and under pressure of the cam this lever is tilted rearwardly about its pivot to raise the forward end of arm 31 to thus tilt table 30 upwardly and backwardly so as to remove the knife being sharpened thereon out of contact with grinding wheel 13. When the cam 50 comes again to its low side the forward end of lever 70 is lowered until it comes to rest on cam 37 where it is in position for grinding the tooth of the knife which is then presented.

Referring more particularly to FIG. 3, the cam 51 bears against the strap 80 which is mounted for longitudinal movement in holder 81. This strap engages at its rearward end a tooth in the wheel 82 and is spring pressed so that after rearward movement under pressure of cam 51, and when the cam comes to its low side, the strap is pulled forwardly again with its rearward end riding over the slanted edge of the next tooth in wheel 82. Wheel 82 has the same number of teeth as the knife to be sharpened so that it turns one complete revolution when all sections of the knife have been sharpened.

Wheel 82 carries on its face a cam 83 on which the strap 84 rides, and when the high side of cam 83 comes suddenly to contact with strap 84 this moves strap 84 to permit switch 85 to move to open position and to stop motor 45.

The cams 49, 50 and 51 are positioned on shaft 48 in the angular positions for performing their various functions in the proper sequence as will be explained in the following recital of the overall operation of the device:

The operator turns on motor 45 which causes the grinding wheel to run continuously. He then takes the skinning knife (designated by the character 100 in FIG. 1) and places it over hub 39 and flat against table 30 in which position the teeth are slanted counterclockwise and have their edges beveled on the under side of the knife. The knife is placed so that one tooth is in proper angular position to be ground by the grinding wheel. The table at this time is in its raised position,

having been stopped in this position at the conclusion of a prior sharpening operation. The knife 100 is held tightly against table 30 by the two permanent magnets 41 and 42.

Then when cam 49 has moved to allow the lever 70 to tilt and to allow table 30 to descend and move about the pivot of arm 31 the grinding wheel comes into contact with the knife and the first tooth is sharpened. Next cam 50 operates to move strap and rod 62 forwardly so that the detent moves the knife angularly a dis tance of one tooth on the circumference of the knife and then retracts with the point of detent 65 sliding over the inclined edge of the tooth. When the knife has been turned to present the next tooth in position for grinding the cam 51 operates to turn the counting wheel 83 one notch, and we come to the next cycle. As the next cycle starts, cam 50 again lowers the knife for grinding the next section or the next tooth of the knife to be sharpened. Then follows the grinding, the raising of the table and the turning of the knife as well as the counting of the second tooth.

When a cycle of operation has been completedas many times as there are teeth on the knife, the cam 83 on wheel 82 operates to turn off the motor 45. I prefer to use a motor 45 with a solenoid brake on its shaft so that the brake applies the instant the circuit is broken to stop the motor almost instantly and prevent over-run into the next cycle.

I find that it is a further advantage that the magnets 41 and 42 are spaced and positioned under the edge portions of the circular knives to be sharpened so that these magnets exert a substantial force tending to resist any tendency of the knife to chatter or vibrate.

I further find it important that the mechanism for turning the knife in an angular direction includes a rod such as rod 62 movably held between the rollers 63. Preferably, the rollers have edge rims providing channels in which the rod is held against excessive movement to one side or up and down, but is yet permitted to move freely in a longitudinal direction.

It is understood that many modifications may be made in the structure herein disclosed and that equivalent structures may be substituted for that described herein without departing from the inventive principles involved; and it is, therefore, intended that all such modifications and equivalents be covered as they are embraced within the spirit and the scope of the invention.

I claim:

1. A device for sharpening disc-type knives comprising a grinding wheel, a table for receiving thereon a knife to be sharpened, means for supporting said table for tiltable movement forwardly about a horizontal axis to bring one section of said knife into engagement with said grinding wheel and backwardly about said axis to remove said section from said wheel, magnet means for attracting said knife to said table in frictional engagement therewith, and means for moving said knife against the frictional force provided by said magnetmeans when said table is in rearward position to pres-- ent another section of said knife for contact with said wheel.

2; A device as set forth in claim 1 wherein said table is provided with a hub and the knife to be sharpened has an aperture into which said hub is received and wherein said means for moving said knife is effective for moving said knife angularly about said hub.

3. A device as set forth in claim 2 wherein said knife is circular and has teeth spaced about its circumference and wherein said means for moving said knife is effective to move said knife angularly about said hub an angular distance equal to the spacing between said teeth 4. A device as set forth in claim 1 including means for driving said moving means and including means sensitive to the number of movements of said moving means for stopping the operation of said driving means when all sections of said knife have been presented for sharpening.

5. A device as set forth in claim 1 wherein said magnet means includes a pair of spaced permanent magbeing operable to tilt said table, and another of said cams being operable to move said knife to present another section for contact with said wheel.

9. In a device for sharpening circular toothed knives, a table adapted to receive a circular knife thereon, a hub on said table adapted to be received within a central aperture of said knife and is effective for guiding said knife when the knife is turned on said table, means for turning said knife angularly about said hub, said turning means including a rod having a detent thereon for engaging a tooth on said knife to move said knife angularly as said rod is moved longitudinally forward, and roller means contacting said rod for restraining said rod against movement in a lateral direction.

110. A device as set forth in claim 9 wherein said roller means includes a pair of rollers on one side of said rod and at least one roller on the other side of said rod, said rollers being in contact with said rod and effective for restraining the rod against lateral movement.

sir a}: n a: 

1. A device for sharpening disc-type knives comprising a grinding wheel, a table for receiving thereon a knife to be sharpened, means for supporting said table for tiltable movement forwardly about a horizontal axis to bring one section of said knife into engagement with said grinding wheel and backwardly about said axis to remove said section from said wheel, magnet means for attracting said knife to said table in frictional engagement therewith, and means for moving said knife against the frictional force provided by said magnet means when said table is in rearward position to present another section of said knife for contact with said wheel.
 2. A device as set forth in claim 1 wherein said table is provided with a hub and the knife to be sharpened has an aperture into which said hub is received and wherein said means for moving said knife is effective for moving said knife angularly about said hub.
 3. A device as set forth in claim 2 wherein said knife is circular and has teeth spaced about its circumference and wherein said means for moving said knife is effective to move said knife angularly about said hub an angular distance equal to the spacing between said teeth
 4. A device as set forth in claim 1 including means for driving said moving means and including means sensitive to the number of movements of said moving means for stopping the operation of said driving means when all sections of said knife have been presented for sharpening.
 5. A device as set forth in claim 1 wherein said magnet means includes a pair of spaced permanent magnets.
 6. A device as set forth in claim 5 wherein each of said pair of magnets is disposed in said table below an edge portion of said circular knife.
 7. A device as set forth in claim 5 wherein said magnets are mounted in said table.
 8. A device as set forth iN claim 1 including a cam shaft and cams mounted thereon, one of said cams being operable to tilt said table, and another of said cams being operable to move said knife to present another section for contact with said wheel.
 9. In a device for sharpening circular toothed knives, a table adapted to receive a circular knife thereon, a hub on said table adapted to be received within a central aperture of said knife and is effective for guiding said knife when the knife is turned on said table, means for turning said knife angularly about said hub, said turning means including a rod having a detent thereon for engaging a tooth on said knife to move said knife angularly as said rod is moved longitudinally forward, and roller means contacting said rod for restraining said rod against movement in a lateral direction.
 10. A device as set forth in claim 9 wherein said roller means includes a pair of rollers on one side of said rod and at least one roller on the other side of said rod, said rollers being in contact with said rod and effective for restraining the rod against lateral movement. 